The invention relates to a wire-stripping plier with an automatic adaptation to various wire gauges and insulation thicknesses with two pairs of pivotable jaws of which the jaws of a first, outer pair are configured as gripper jaws and that are pivotable by means of a first jaw arm and a jaw part about a common point, and the jaws of the other, inner pair that are configured as cutting jaws with blades that cut into the insulation, and with a pull rod attached to the cutter jaws and longitudinally moveable within the jaw body providing the stripping motion that is coupled with a second plier arm.
There are many pliers and similar hand tools used to strip the insulation from electric cables. Compared with traditional cable cutters, adjustable or pre-set wire-stripping pliers offer improved safety for the user and for the cable material. In order to maintain a high-quality connection, it must be ensured that the electrical conductor (single or multi) remains undamaged during stripping. For this, the most important issue is that the sheathing at the end of the cable, and of the individual conductors, may be removed in the contact area cleanly and at the proper length. The great advantage of a conventional automatic wire-stripping plier is the option of pre-cutting and then stripping the insulation in one step by means of further compression of the plier handgrips. Adaptation to varying insulation and cable thicknesses had to be achieved via manual adjustment of the plier, or by provision of multiple blades of varying shapes. Improper operation or adjustment always presented a hazard of conductor damage.
For example, DE 44 20 006 A1 describes a plier to strip conductor ends with an outer pair of holding jaws and inner pair of cutting jaws. Limited adaptation to the wire gauge is achieved by means of the resistance that the holding jaws encounter when compressed. For cables of very small gauge, the compression is limited by an additional limiter. However, adaptation to varying thicknesses of insulation materials was not possible. The danger arises that hard insulation is cut too shallowly, or soft insulation is cut too deep. The result may be that irregularities arise to the cable to be stripped, or to an individual conductor.
EP 0 645 861 A2 describes a stripping plier with two pair of pivotable jaws from which the jaws of the outer pair are implemented as gripper jaws and the jaws of the other, inner pair are implemented as cutter jaws with blades that cut into the insulation. Adaptation to varying conductor gauges and insulation thicknesses is enabled via a cam. By rotating the cam, the user may alter the position the lower cutter jaw and thereby that of the corresponding cutter blade.
DE 44 20 050 C1 describes a wire-stripping plier in which at least one cutter jaw includes a packet of adjacent strips with cutter edges moveable perpendicular to the jaws longitudinal direction that, when the plier is closed, press into the insulation. The strips are supported by means of a clamp arm with a V-shaped recess. Adaptation to varying conductor gauges is performed in that the recess is narrower or wider. To strip conductors of varying gauges, it is necessary to provide clamp arms with varying recesses that must be selected by the user and inserted into the wire-stripping plier.